WASHINGTON (CN) – The Justice Department’s inspector general said Wednesday that it failed to identify who leaked a sensitive UK intelligence report about the 2017 Manchester Arena bombing, but that four FBI employees violated agency policy by forwarding the sensitive report.

The investigation of the matter was prompted by a May 24, 2017, New York Times story, which the inspector general said contained unclassified but sensitive and non-public information from the report, which had been sent to foreign law enforcement agencies, including the FBI.

UK officials disseminated the report in the wake of the May 22, 2017 suicide bombing, which killed 22 concertgoers leaving a performance by American singer Ariana Grande.

The Islamic State group later claimed responsibility for the deadly attack.

An Oct. 10 investigative summary from the inspector general does not identify the specific New York Times story it is referring to, but a story published in the newspaper that day contains photographs from the crime scene.

Given that more than 1,000 FBI employees received the UK intelligence report, the inspector general said the investigation focused on whether any FBI employees had contact with the Times reporter who wrote the story, or had forwarded the report to a non-government email address.

Those efforts, however, failed to identify who leaked the report to the Times reporter, as did the FBI’s analysis of internal email records, telephone logs and agency text messages.

“The OIG investigation found that some FBI personnel forwarded the UK intelligence report to non-government e-mail accounts but the investigation did not identify evidence that any of these individuals provided the report to the” New York Times, the investigative summary says, abbreviating office of the inspector general.

What the investigation did find is that two FBI employees violated the department’s rules for computer use by forwarding the report to their personal email accounts, though neither was found to have given the report to the New York Times reporter.

An FBI task force officer meanwhile forwarded the report to a foreign law enforcement partner prior to getting permission to do so, and without the agency’s warnings that dissemination of the report should be limited.

“The task force officer, during the one year period before the Manchester report was leaked, forwarded three other FBI emails containing operationally sensitive information to unauthorized recipients,” the investigative summary says.

A fourth FBI employee tried to auto-forward the report to their personal email account but internal email filters blocked the action.